The present invention relates to the power supply systems for providing power to a ship. More particularly, the invention relates to power production modules adapted to be connected to a ship to supply the power necessary for their propulsion and their operation.
These days, numerous ships comprise propulsion means fed by a power production plant. Most of the time, such a plant is mounted fixed on the ship itself. But it can be advantageous, according to the type of ship or production plant, for the plant to be decouplable from the ship, especially in the case of nuclear propulsion ships. In fact, the use of nuclear energy can create substantial restrictions, such as being denied access to some ports, lengthy immobilisation of the ship during maintenance of the plant or reloading of fuel, etc.
Power production plants mounted on an independent ship have therefore been proposed. Document WO 01/49562 proposes an assembly of ships comprising especially a barge and a pusher ship fitted with propulsion means fed by a power production plant. The rear part of the barge complements the form of the front part of the pusher ship to make a mechanical interconnection so that said barge is pushed and moved by the pusher ship. One limitation to this solution is that it does not allow the barge to move independently of its pusher. Also, the size of such an assembly of ships is generally limited, especially because of the dissipation of energy at the level of the mechanical interconnection.
Document GB 949 645 has also proposed deploying an assembly of decouplable ships comprising a power supply ship and at least one satellite ship, each being fitted with its own propulsion means. The energy produced by the supply ship is transferred to the satellite ship by means of electric cables, creating relative independence for ships making up the ensemble. Each satellite ship further comprises an additional power production plant allowing it to decouple temporarily from the supply ship, and can be a submarine or a large boat. However, displacement of the supply ship and of the satellite ship or ships can be complicated, for example when weather conditions are poor, and make it difficult to execute the transfer of power. Further, the energy necessary for moving the supply ship and the satellite ship is greater than the power needed to move a single ship.
The aim of the invention is therefore to rectify these difficulties posed by the prior art. For this, the invention proposes a power production module decouplable from a ship, capable of providing the ship with a power necessary for its propulsion, which can be adapted to any type of ship, and in particular to large ships such as cargo freighters, container ships or passenger ships.
Another aim of the invention is to propose a power production module decouplable from a ship enabling simple transfer of power and in all circumstances, especially when weather conditions are difficult. So, according to a first aspect, the invention proposes an electric power production module for a main ship able to supply the power necessary for propulsion of said main ship,                the module being made in the form of a secondary ship independent of the main ship and comprising a power production plant,        the secondary ship being fitted with electrical connection means for making an electrical connection between the plant and the main ship and locking means on the main ship to make it solid with said main ship when in motion, in which the electrical connection means are adapted to supply propulsion means of the main ship with electric power.        
Some preferred, though non-limiting, aspects of the power production module according to the invention are the following:                the secondary ship further comprises propulsion means allowing it to move independently of the main ship; and        the power production plant is a nuclear plant, a gas plant or a hydrogen plant.        
According to a second aspect, the invention proposes an assembly of ships comprising a main ship and a secondary ship, said secondary ship being a module according to the invention, the main ship comprising means for receiving the secondary ship.
Some preferred, though non-limiting, aspects of the assembly of ships according to the invention are the following:                the means for receiving the secondary ship are located in a rear or lateral part of the main ship;        the main ship comprises a receptacle whereof the form complements the form of the secondary ship, so that when the locking means lock the secondary ship onto the main ship, the secondary ship does not present a surface opposing the advance of the assembly of ships;        when the locking means lock the secondary ship onto the main ship, the secondary ship remains launched;        the locking means of the main and secondary ship are configured so that when the locking means lock the secondary ship onto the main ship, the secondary ship is pulled by the main ship;        the main ship comprises a invert enabling it to receive the secondary ship in an internal space; and        the main ship comprises an additional power production plant designed to feed the propulsion means of the main ship in port, the propulsion performance then being substantially less than when said propulsion means of the main ship are fed by the plant of the secondary ship.        